In a 3.9G mobile communication system referred to as LTE (Long Term Evolution), to reduce maintenance and operation work of telecommunications carriers, introduction of a technique referred to as SON (Self Organizing Network) is being proposed.
If a radio base station apparatus needs to temporarily halt transmission of radio waves because of failures, malfunctions, software updates, or the like, the radio base station apparatus cannot continue to provide services in the coverage area thereof. Based on one function referred to as the SON, for example, neighboring radio base station apparatuses change the antenna tilts and increase the reference signal transmission power, to temporarily expand coverage areas of the neighboring radio base station apparatuses. Namely, a method of temporarily complementing the coverage area of a radio base station apparatus that halts transmission of radio waves is being discussed (see FIG. 7).
For example, a maintenance and monitoring apparatus, which is an upper apparatus of radio base station apparatuses 100 to 102 in FIG. 7, monitors states of these subordinate radio base station apparatuses 100 to 102. For example, if the maintenance apparatus detects a failure in the radio base station apparatus 101, the maintenance apparatus instructs the neighboring radio base station apparatuses to expand the coverage areas thereof, as illustrated in FIG. 7(2). In this way, services in the cell area of the radio base station apparatus 101 can be provided continuously.
Patent Document 1 discloses a mobile communication system in which each radio base station apparatus automatically changes the size of the cell thereof, depending on the traffic amount in the cell. Based on a function of this mobile communication system, if the operation of a cell is halted, neighboring cells cover the area of the halted cell, so that services in the area can be provided continuously.
Patent Document 1:
Japanese Patent Kokai Publication No. JP-P2006-101442A